Question

Choose the odd one out. Give reasons for the choice.

Sand in water, powdered chalk in water, Fog, Dust in air.

Answer 1

Types of solutions:

Suspension	Colloids
Suspensions are heterogeneous mixtures. The particles in a suspension are larger than that of a solution and these particles can be separated by filtration process. When the suspension is kept undisturbed, the particles settle down. Examples of suspensions: Sand in water, Powdered chalk in water, Dust in air	Colloids are heterogeneous mixtures. Every colloid contains two parts - colloidal particles (dispersed phase) and dispersing medium. The particles of colloids (solid or liquid) will have intermediate sizes between suspension and solution particles. The particles of colloids do not dissolve but get dispersed in the medium and cannot be separated by filtration. Example of colloids: Fog

Therefore, Fog is an odd one because it is a type of colloid while all others are suspension.